US3838921A

US3838921A - Photoelectrostatic copying apparatus

Info

Publication number: US3838921A
Application number: US00160514A
Authority: US
Inventors: J Sargis
Original assignee: Multigraphics Inc
Current assignee: AB Dick Co
Priority date: 1969-02-27
Filing date: 1971-07-07
Publication date: 1974-10-01
Anticipated expiration: 1991-10-01

Abstract

Apparatus comprising an illuminating source for use in a copying machine of the type including a photoconductive recording member from which copies are made by the transfer of developed images from the member to copy sheets. The illuminating source is used to discharge the photoconductive surface of the recording member thereby to loosen unwanted toner adhering electrostatically to the surface of the member.

Description

United States Patent Sargis Oct. 1, 1974 PHOTOELECTROSTATIC COPYING APPARATUS [75] Inventor: John R. Sargis, Chicago, Ill. [73] Assignee: Addressograph-Multigraph Corporation, Mount Prospect, Ill.

[22] Filed: July 7, 1971 21 Appl. No.: 160,514

Related US. Application Data [62] Division of Ser. No. 803,000, Feb 27, 1969.

[52] US. Cl. 355/15 [51] Int. Cl G03g 15/00 [58] Field of Search 355/3, 15; 96/1 [56] References Cited UNITED STATES PATENTS 2,968,553 l/l96l Gundlach 96/1 3,122,455 2/1964 Grimm 355/3 x Primary Examiner John M. Horan Attorney, Agent, or Firm-S0l L. Goldstein; Michael A. Kondzella [57] ABSTRACT Apparatus comprising an illuminating source for use in a copying machine of the type including a photoconductive recording member from which copies are made by the transfer of developed images from the member to copy sheets. The illuminating source is used to discharge the photoconductive surface of the recording member thereby to loosen unwanted toner adhering electrostatically to the surface of the memher.

3 Claims, 1 Drawing Figure PHOTOELECTROSTATIC COPYING APPARATUS BACKGROUND OF THE, INVENTION This invention relates generally to electrostatic copying apparatus and more particularly to copying apparatus employing a photoconductive member from which developed images are transferred to produce copies.

In copying machines utilizing members having photoconductive properties from which a developed image is transferred to a copy sheet, such as, for example, in the case of a copying machine using an endless belt member having a photoconductive surface, as shown in copending patent application of Loren E. Shelffo, Henry A. Mathisen, and Frank L. Schwager entitled PHOTO- ELECTROSTATIC DUPLICATOR, Ser. No. 762,617, filed Ian. 21, i969, assigned to the same assignee, now US. Pat. No. 3,606,532, a quantity of developing powder often remains on the photoconductive surface of the member subsequent to the transfer of the developed image from the latter to a copy sheet. When this occurs, the powder remaining can cause copies made subsequently from the photoconductive member, when imaged from other originals, to be smeared or unclear. As the photoconductive member is used over and over again, additional developer powder build up occurs, making later made copies even more unclear.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide in an electrostatic copying machine using a photoconductive member from which developed images are transferred to produce copies, new and improved means for freeing-up toner powder remaining on the photoconductive member after transfer of a developed image to a copy sheet.

It is a more specific object of this invention to provide a predeterminedly positioned illuminating source adjacent a photoconductive member in a copying machine of the abovedescribed type, which serves to loosen toner particles adhering to the member, subsequent to the completion of the development step of the copy making cycle.

It is a further object of the present invention to provide, in an electrostatic copying machine of the type which uses a photoconductive belt member for producing copies of graphic originals and which is capable of providing multiple copies of a given original from the repeated development of a latent image of the original produced thereon, a predeterminedly located illuminating source for thoroughly loosening electroscopic developer powder remaining on the photoconductive member subsequent to the development of the last of the multiple copies.

It is yet another object of the present invention to provide an improved method for freeing up toner pow der clinging to the photoconductive surface of a re cording member from which developed images are transferred to produce copies.

It is still another object of the present invention to provide in a copying machine including a photoconductive recording member from which developed images are transferred to produce copies, an improved method of removing excess toner clinging to said member subsequent to a copy making cycle.

Briefly, a preferred embodiment of the toner removing apparatus according to the invention comprises an illuminating source, such as. for example, a fluorescent light tube having a reflector shield extending partially thereabout, located adjacent the photoconductive member in a copying machine. The light source is operated when required to photoelectrically loosen unwanted toner particles remaining on the surface of the member. Loosened toner particles are removed during the ordinary cycle of copy making and/or by the attraction of the particles to the developing means subsequent to the copying cycle, depending upon the location of the light source.

In an electrostatic copying machine of the type using a transparent photoconductive belt member, the illuminating source is located preferably adjacent the back or support surface of the belt member so as to radiate through the belt member. In the case of an opaque belt member, the radiation source is mounted adjacent the photoconductive surface of the belt member so as to illuminate the photoconductive surface directly.

DESCRIPTION OF THE DRAWINGS A better understanding of the present invention and its organization and construction may be had by referring to the description below in conjunction with the accompanying drawing, wherein the single FIGURE is a side sectional view of a diagrammatic representation of a copying machine employing apparatus for removing unwanted toner from the photoconductive member thereof according to the invention.

DETAILED DESCRIPTION An example of an electrostatic copying machine in which apparatus for removing toner from the photoconductive member thereof may be used according to the invention is illustrated in the single FIGURE of the drawings, and is designated generally by the numeral 10. The copying machine 10 includes an outer housing 12 having an upper wall 14 and a base wall 16 joined by a pair of end walls 18 and a pair of side walls 20, only one of which is shown. The upper or top wall 14 of the housing 12 includes an opening 22 into which there has been placed a transparent platen 24, of glass or similar material. The platen 24 is mounted at opposite sides thereof in a pair of guide channels 26 connected to the upper wall 14 and extending inwardly into housing 12. Thus, the platen is substantially coplanar with the outer surface of the top wall of the housing.

A photoconductive member, generally designated by the numeral 28, herein taking the form of an endless belt 30, having an organic photoconductive surface 31, is mounted for counterclockwise movement as indi cated by the arrows along a predetermined path, on a plurality of predeterminedly spaced rollers or

pulleys

32, 34, and 36. In the vicinity of roller 32 adjacqnt belt 30, there is located a charging station 38, comprising a corona unit 40 of the well-known type, for charging the photoconductive surface 31 of the belt 30. Counterclockwise about the belt from charging station 38, there is mounted an optical assembly 42, including a pair of inclined reflecting mirrors 44 and 46 and a lens 48 interposed therebetween. Light from light sources 50 mounted within housing 12 adjacent platen 24, is

reflected from an original 'placed on the platen from which copies will be made, and transmitted via optical assembly 42 to a given area, defined by reflected

light rays

52, 54 on belt member 30 to comprise an exposure station 56 for selectively discharging the charged photoconductive surface of the belt, thereby to form a latent image on the latter.

A developing station 58 including a magnetic brush developer 60 of a well-known type immersed in a container of toner particles 62, is provided near roller 34 upon which belt 30 is mounted. The developing station 58 is immediately counterclockwise about belt 30 from exposure station 56 as shown in the FIGURE Toner particles or developer powder from the magnetic brush 60 are depositqd on the charged image areas of the belt 30 as the belt passes adjacent the developing station.

A copy sheet stack 68 is provided at the left of the copying machine as seen in the FIGURE. Single sheets 70 are fed from the stack in synchronization with the movement of belt 30 about

rollers

32, 34, 36. Initially, the feed roller 72 moves the top sheet of the stack 68 in the direction of the arrow toward roller pair 74. The roller pair continues to move the sheet along the copy sheet path 76 until the leading edge thereof reaches roller 36. At this time, the developed image on belt 30 is also coming about and a leading edge of the imaged portion thereof is nearing roller 36.

A transfer roller 78 charged electrically by power supply 79, is mounted for rotation adjacent roller 36 and belt 30 to form therewith a transfer station 80. The roller 78 serves to move a copy sheet along the copy sheet path of the machine as well as to maintain the copy sheet in close proximity to the moving belt carrying the toner particles so that the particles will be transferred from the belt to the sheet. The electrical charge of transfer roller 78 is opposite in polarity to that of the toner particles so that the latter are attracted from the belt towards the roller 78. Normally, a copy sheet will be interposed between transfer roller 78 and belt 30 so that the particles will be deposited on the upper surface of the copy sheet as they leave the imaged areas of the photoconductive member.

From the transfer station 80, the copy sheet is carried via a conveyor belt arrangement 82 including an endless belt member 84 mounted for movement on

spacedapart rollers

86, 88 to a fuser device 90. As the copy sheet passes through the fuser 90, the developer powder is heated and thereby caused to permanently adhere to the surface of the copy sheet, thereby to produce a completed copy. From the fuser the completed copy is carried out of the copying machine into an inclined tray 92 provided on the outside of the machine.

The particular copying machine shown in the drawing also includes apparatus generally designated by the numeral 94 for removing toner particles which have accumulated on the surface of transfer roller 78 so as to at all times maintain the transfer roller surface toner-free, thereby to avoid the smearing of toner onto the back surfaces of copy sheets passing through the transfer station. A more detailed description of the transfer roller cleaning apparatus 94 can be found in co-pending patent application of John R. Sargis entitled TONER CLEANING APPARATUS FOR A PHO- TOCOPY MACHINE, Ser. No. 794,213, filed Jan. 27. I969 now US. Pat. No. 3,713,736.

In operation the above-described copying machine is capable of making a single or multiple copies of a graphic original placed face downwardly on the platen In preparing a single copy, the original is first placed on the platen 24 as described above. The machine is then energized so that belt member 30 is moved in a counterclockwise direction about mounting rollers 32. 34, and 36. In the usual manner. belt member 30 is moved past charging station 38 whereat a uniform electrical charge is imparted to the photoconductive surface thereof. The charged photoconductive layer is selectively discharged at exposure station 56, and is developed by the application of toner particles to the latent electrostatic image as it passes developer station 58. The developed image is then transferred to a copy sheet passing through the transfer station in synchronism with the movement of the photoconductive belt member, and the transferred image is then fused or fixqd to the copy sheet, subsequently, as the copy sheet passes through the fusing station 90.

For multiple copy reproductions of an original. the photoconductive surface of the belt member, which as mentioned above is of an organic photoconductive material, need not be reimaged since the latent image formed initially on the belt member is not lost. Consequently, many copies of a single original may be made without recharging or reexposing the photoconductive surface of the belt. The latent image initially formed on the belt member requires merely developing and transfer to a copy sheet.

A more detailed description of the operation of the copying machine can be had by referring to abovementioned copending patent application Ser. No. 762,617, now US. Pat. No. 3,606,532.

Upon completion of a copying cycle using a photoconductive graphic original, whether belt be after the reproduction of a single copy of the original or after the reimaged of a series of copies, a quantity of toner particles often remains on the photoconductive surface of the belt member. adhering electrostatically thereto. Consequently, upon reimaging the photoconductive surface from another graphic original. the toner remaining on the belt the causes the requires of redeveloping second original to be smeared or unclear.

Thus, there has been provided herein a toner loosening means taking the form of an illumination source, to aid in freeing up the photoconductive surface of the belt of toner prior to making copies of a subsequent graphic original.

The light source serves well to free up unwanted toner particles clinging to the photoconductive surface. The radiation from the light source discharges and destroys or neutralizes the electrically charged image areas of the photoconductive surface of the belt member, causing the release of the electrostatic forces holding the particles thereto.

In the case where the belt member 30 is of the transparent or translucent type, a light source 96 may be located immediately downstream of the developer station 58 and upstream of the transfer station adjacent the back or base support 33 of the belt member. When the belt member is opaque, a light source 98 may be located upstream of the charging station 38 and adjacent the photoconductive surface 31 itself.

In either of the two locations mentioned above, the illuminating source may take the form of a fluorescent tube 100, the axis of which extends transverse to the direction of movement of the belt member 30, and including a semi-cylindrically shaped reflector and shield 102 extending the length of and partially surrounding the light tube so as to direct light produced by the latter toward the belt member 30 and to prevent the light from radiating into other areas of the copying machine whereat it might produce deleterious results. The fluorescent tube is preferred over an incandescent or the like light source since the former produces less heat, which might be transmitted to the recording member 30. In addition to the reflector-shield 102, a second shielding means 104 is provided in the case wherein a light source, such as 96, is placed adjacent developer station 58, to prevent poor development of latent images produced on the photoconductive member from light radiating into the developer zone from source 96.

A light source of approximately 30 watts placed at a distance of 3 5 inches from the belt has been found to produce good toner loosening results in either of the two locations described. Light sources of other wattages placed at different distances from the belt member, however, will produce equally good results. In practice the combination of light source 96 and a trans lucent or transparent belt member 30 proves to be slightly more effective, since the light emanating from the source need not pass through the toner itself as in the case of an opaque belt and the use of source 98.

For purposes of affording a more complete understanding of the invention, it is advantageous now to provide a description of the operation of the structural elements heretofore described.

SINGLE COPY MODE In the case wherein copying machine is set to produce a single copy of a graphic original, the photoconductive surface 31 of the belt member 30 is charged, imaged, developed and the developed image is transferred and fixed as described heretofore. If the belt member is translucent or transparent, an illuminating source is positioned at the location of source 96. In this case, the light source is operated subsequent to the development of the electrostatic image and immediately prior to the transfer of the developed image to a copy sheet moving in synchronism with the movement of the belt member. Thus, the electrostatic image is discharged and the toner clinging thereto is freed. The toner, however, does not separate from the belt member, but remains in the position thereon in which it was depositqd by developer brush 60. When the developed image reaches the charged transfer roller 78, the toner is attracted thereto and deposited on a copy sheet interposed between the roller 78 and the moving belt member. Because the illuminating source, through the action of the radiation emanating therefrom, has thoroughly loosened the toner particles, substantially all of the particles are transferred to the copy sheet, leaving the photoconductive surface 31 of the belt member substantially toner free. In the event some toner does remain on the belt member, it will be removed by developer brush 60 as that portion of the belt member passes thereby on the following revolution,

Where the belt member 30 is opaque, a light source positioned at the location of source 98 is utilized. In the single copy mode, a light source such as 98 is energized subsequent to the transfer of the developed image at transfer station 80, since any toner particles remaining after transfer of the developed image are removed upon passage of the specific area of the belt member past the developer station 58; the area not being recharged at station 40 immediately after passing transfer station 80. Due to the forces between any remaining toner particles and the magnetic brush 60 of the developing station 58, the toner particles are attracted from the discharged photoconductive surface 31 to the magnetic brush and consequently are removed from belt 30.

MULTIPLE COPY MODE In the multiple copy mode belt member 30 as mentioned before need only be charged and imaged once to provide a desired number of copies of an original. Many copies may be made by simply redeveloping the image thereafter.

Use of the illuminating source in the multiple copy mode does not occur until the last copy has been developed, since any use of the source prior to the development of the last copy destroys the latent image. making it impossible to produce new copies without again charging and exposing the photoconductive surface of the belt member 30.

Thus, in the case wherein a translucent or transparent member 30 is used in the copying machine 10, as the developed image to be transferred as the last copy passes from the developing station 58, the illumination source 96 is energized. The toner is loosened from the attractive force of the latent image due to the discharging of the latter by the radiation from source 96, preparing the toner for transfer to the last copy sheet of the multiple copies being made. The toner, being loosened, passes easily toward the charged transfer roller 78 to a copying sheet interposed between the belt member 30 and the roller 78, removing substantially all the toner from the belt member. As in the case of the single copy mode, any toner remaining on the belt member will be attracted to the developer brush 60 on the next revolution of belt member 30.

In the case where the photoconductive recording member 30 is opaque, the light source 98 is utilized and is energized subsequent to the transfer of the developed image used for preparing the last copy of the desired number of copies of the single original. Any toner remaining on the photoconductive surface 31 of the belt member after the transfer, is freed up, due to the discharge of the latent image by means of the illuminating source 98, and the toner is subsequently removed by the action of the magnetic developer brush 60 thereagainst as the belt member passes thereby. As in the case of the single copy mode, the area of the belt member having had the latent image thereon, is not recharged at station 40 immediately. but passes the sta tion at least once prior to recharging.

Thus, the toner freeing apparatus comprising an illuminating source according to the invention, positioned as indicated heretofore. provides a simple efficient and inexpensive means for clearing the photoconductive surface 31 of a recording member of unwanted toner particles which would otherwise cling to the surface and possibly cause subsequent images prepared from other originals to be smeared or unclear.

While particular embodiments of the invention have been shown and described, it should be understood that the invention is not limited thereto since many modifications may be made. It is therefore contemplated to cover by the present application any and all such modifications as fall within the true spirit and scope of the appended claims.

What is claimed is: 1. In a copying machine comprising a source of copy charging means positioned at a predetermined location along the path of said endless member for electrically charging the photoconductive surface of said recording member material, exposure means located downstream of said charging a translucent recordlf'lg member havmg a ph f means along the path of said endless member for ductlve Surface, 531d recofdmgmember Including selectively discharging said photoconductive suratranslucent base supporting said photoconductive f to provide a charged image f an original Surface, thereon, Charging means for electrlcauy chafgmg the P 10 developing means mounted downstream of said exconductwe Surface of salld recwdmg m b posure means along the path of movement of said exposure mefans for Selective! dlschargmg endless member for applying toner to said member, tocorldllctwe surface to Provlde a charged Image of whereby the toner is attracted to said charged iman orlginal thereon, age and developmg "t for iipplymg to Sald member transfer means located downstream of said developwhereby said toner lS electrostatlcally attracted to ing means along the path of movement of said Bald Charged Image and less member and including means for attracting transfer means for transferring said developed image f b to Said py material sai toner rom sai recor mg mem er to copy material interposed between said transfer means and means for freeing toner from said recording member the hotoc nductiv Surf, of Said endless mem to prevent copies made subsequently from other b p O c ace originals from receiving toner remaining on said f l t f d h t d recording member after said developed image has meal: or i ig tom 0 (Leon been transferred to said copy material comprising 1 0 recor mg g er t 6 en 0 an illuminating source positioned adjacent the base Copymg eye 6 Prevent Subsequently Support of Said recording member and opsrable to from other originals from receiving toner remamradiate through said base support to illuminate the mg Sald photocondilstwe Surfacesald photoconductive surface of said recording member IPOSemHEFeaHS CPmPnSmg a Source of f" to destroy said charged image and the electrostatic PQSltlOned adlacem the base PP of 531d attractive force thereof securing the toner thereto. rePordmg member p to radiate through said base support to illuminate the photoconduc- 2. in a copying hi comprising a source f copy tive surface of said recording member to destroy material, said charged image and the electrostatic attractive a translucent recording member having an organic force e eo Securing the toner thereto.

photoconductive surface, said recording member 3 3. A copying machine according to claim 2 wherein including a translucent base supporting said photosaid illuminating source is disposed immediately downconductive surface and taking the form of an endstream of said developing means along the path of less member mounted for movement along a predemovement of said recording member. termined path,

UIN ITEI STATES PATENT OFFICE CERTIFICATE. OF. CORRECTION Patent No. 3,838,921 Dated October 1, 1974 InventorU) John R. Sargis It is certified that errorappears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 59, change "adjacqnt" to adjacent Col. 3, line 13, insert after "FIGURE".

.3, line 15, change "depositqd" to deposited Col.

Col. 4, line 20, change "fixqd" to fixed Col. 4, line 30, change "developing" to redeveloping Col. 4, lines 36-46, This paragraph should read as follows:

- "Upon completion of a copying cycle using a first graphic original, whether it be after the reproduction of a single copy of the original or after the last of a series of copies, a quantity of toner particles often remains on the photoconductive surface of the belt member, adhering electrostatically thereto. Consequently, upon reimaging the photoconductive surface from another graphic original, the toner remaining on the belt member causes the copies of the second original to be smeared or unclear."

Col, 5, line 50, change "depositqd" to deposited Signed and sealed this 3rd day of December 1974.

(SEAL) Attest McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-105O (10-69) USCOMM-DC 60376-P69 us sovsauuem' mm'rmc orncz 1 i969 o-ais-su UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,838,921 I Dated October 1, 1974 Inventor) I John R. Sargis It is certified that errorappears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 59, change "adjac'qnt" to adjacent Col. 3, line 13, insert after "FIGURE". Col. 3, line l5,-change "depositqd" to deposited Col. 4, line 20, change "fix'qd" to fixed Col. 4, line 30, change "developing" to redeveloping Col. 4, lines 36-46, This paragraph should read as follows:

I "Upon completion of a copying cycle using a first graphic original, whether it be after the reproduction of a single copy of I the original or after the last of a series of copies, a quantity of toner particles often remains on the photoconductive surface of V the belt member, adhering electrostat-ically thereto. Consequently,

upon reimaging the photoconductive surface from another graphic original, the toner remaining on the belt member causes the copies of the second original to be smeared or unclear."

Col. 5, line 50, change "depositqd" to deposited Signed and sealed this 3rd day of December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. 'c.' MARSHALL DANN- Attesting Officer I Comissioner of Patents F ORM PO-105O (10-69) USCOMM'DC 60376-969 k 'US, GOVERNMENT PRINTING OFFICE i969 0-366-334

Claims

1. In a copying machine comprising a source of copy material, a translucent recording member having a photoconductive surface, said recording member including a translucent base supporting said photoconductive surface, charging means for electrically charging the photoconductive surface of said recording member, exposure means for selectively discharging said photoconductive surface to provide a charged image of an original thereon, developing means for applying toner to said member whereby said toner is electrostatically attracted to said charged image, and transfer means for transferring said developed image to said copy material, means for freeing toner from said recording member to prevent copies made subsequently from other originals from receiving toner remaining on said recording member after said developed image has been transferred to said copy material comprising an illuminating source positioned adjacent the base support of said recording member and operable to radiate through said base support to illuminate the photoconductive surface of said recording member to destroy said charged image and the electrostatic attractive force thereof securing the toner thereto.

2. In a copying machine comprising a source of copy material, a translucent recording member having an organic photoconductive surface, said recording member including a translucent base supporting said photoconductive surface and taking the form of an endless member mounted for movement along a predetermined path, charging means positioned at a predetermined location along the path of said endless member for electrically charging the photoconductive surface of said recording member, exposure means located downstream of said charging means along the path of said endless member for selectively discharging said photoconductive surface to provide a charged image of an original thereon, developing means mounted downstream of said exposure means along the path of movement of said endless member for applying toner to said member, whereby the toner is attracted to said charged image, and transfer means located downstream of said developing means along the path of movement of said endless member and including means for attracting said toner from said recording member to copy material interposed between said transfer means and the photoconductive surface of said endless member, means for loosening toner from said photoconductive surface of said recording member at the end of a copying cycle to prevent copies made subsequently from other originals from receiving toner remaining on said photoconductive surface, said toner loosening means comprising a source of illumination positioned adjacent the base support of said recording member and operable to radiate through said base support to illuminate the photoconductive surface of said recording member to destroy said charged image and the electrostatic attractive force thereof securing the toner thereto.

3. A copying machine according to claim 2 wherein said illuminating source is disposed immediately downstream of said developing means along the path of movement of said recording member.